Indexing Classes

Creating a Persistent Index Using the API

The following example demonstrates indexing a class and persisting the index to disk. The resulting file can later be loaded and used.

Indexer indexer = new Indexer();
indexer.indexClass(Map.class);
Index index = indexer.complete();

try (FileOutputStream out = new FileOutputStream("/tmp/index.idx")) {
    IndexWriter writer = new IndexWriter(out);
    writer.write(index);
}

Loading a Persistent Index

The following example demonstrates loading the index from the previous example and using that index to print all methods on java.util.Map:

Index index;
try (FileInputStream input = new FileInputStream("/tmp/index.idx")) {
    IndexReader reader = new IndexReader(input);
    index = reader.read();
}

ClassInfo clazz = index.getClassByName(DotName.createSimple("java.util.Map"));

for (MethodInfo method : clazz.methods()) {
    System.out.println(method);
}

Creating a Persistent Index Using the CLI

The following example demonstrates indexing hibernate core, followed by the entire Java JDK 8 using Jandex on the CLI:

$ java -jar jandex-2.4.2.Final.jar hibernate-core-6.0.0.Final.jar
   Wrote hibernate-core-6.0.0.Final-jar.idx in 0.9170 seconds
         (5746 classes, 50 annotations, 2995 instances, 61729 class usages, 1737428 bytes)
$ java -jar jandex-2.4.2.Final.jar rt.jar
   Wrote rt-jar.idx in 1.7310 seconds
         (20226 classes, 57 annotations, 2476 instances, 246298 class usages, 5890787 bytes)

The above summary output tells us that this version of Hibernate ORM has 5,746 classes, and those classes contained 2,995 annotation declarations, using 50 different annotation types. The resulting index is 1.7 MB uncompressed, which is only 19% of the 9.0MB compressed jar size, or 4% of the uncompressed class file data. If the index is stored in the jar (using the -m option) it can be compressed an additional 43%, leading to a jar growth of only 11%.

Using the Ant Task to Index Your Project

The following Ant task can be used with either the maven-antrun-plugin or an Ant build to build an index for your project:

<taskdef name="jandex" classname="org.jboss.jandex.JandexAntTask"/>
<jandex run="@{jandex}">
    <fileset dir="${location.to.index.dir}"/>
</jandex>

Using the Maven Plugin to Index Your Project

See Basic Maven Plugin Usage.